The long-term goal of this study is to determine whether HIV-I based vectors can prevent AIDS disease progression in HIV-infected individuals. We have shown that an HIV vector carrying an anti-HIV antisense genetic payload (VRX496) can transduce primary human CD4 T cells by over 90 percent transduction efficiency, as measured by FACS two weeks after transduction. CD4 T cells transduced in this manner were directly challenged with wt-HIV and shown to inhibit HIV-I replication in normal primary CD4 T cells by over three logarithmic units of p24. Similar inhibitory effects on wt-HIV replication were seen when transduced cells were challenged with various primary strains of HIV. Significantly, primary CD4 T cells transduced with VRX496 were found to be resistant to productive HIV infection and hence, had a survival advantage over cells not modified with the vector. Furthermore, preliminary data have shown similar effects of VRX496 in CD4 T cells derived from one HIV-infected donor. An important goal for the clinical translation of this class of vectors would be to characterize their inhibitory effects on the pathogenic virus present in cells derived from HIV-infected individuals. The specific goal of this project is to fully characterize the inhibitory effects of VRX496 in primary human CD4 T cells derived from HIV-infected donors that differ by their clinical status. CD4 T cells isolated from HIV infected donors discordant in viral load, CD4 count and HAART therapy will be transduced with VRX496 and the biological and anti-HIV effects characterized. Characterization of the effects of VRX496 in the cells from a wide variety of HIV-infected patients ex vivo will provide important data for rational design of future in vivo clinical studies. PROPOSED COMERCIAL APPLICATIONS: HIV-1 based vectors can deliver payload genes into primary human cells with very high efficiency. When a anti-HIV payload gene is deliv ered into primary CD4+ T cells that are then infected with wt-HIV, viral replication can be inhibited by over 2 logarithmic units of p24, as measured by ELISA antigen capture assay. One of the potential commercial applications of the technology is for the treatment of individuals infected with AIDS. The technology can also be used for gene therapy of other diseases such as cancer because this class of vectors can efficiently transduce many cell types.